When an artificial blood vessel, i.e., a graft, is connected between an artery and a vein to act as a shunt, a tubular polytetrafluoroethylene graft is commonly used. However, many patients with a graft of this kind develop dialysis graft intimal hyperplasia (GIH), a condition in which cells lining the vessels grow at a high rate thereby blocking the vessel. Although efforts have been made to reduce or eliminate hyperplasia of the dialysis graft, none of the proposed solutions have been entirely satisfactory.
Various attempts have been made to address this problem. For example, U.S. Pat. Nos. 5,658,894; 5,786,326; 5,874,419; 6,136,798; 5,935,940; 5,902,799; 6,605,115; 6,689,803 and 6,726,923 describe drugs, biologicals and other pharmaceutical preparations that can be used for treating intimal hyperplasia, but these substances must be taken internally or applied to the occluded vessel. Consequently, these treatments have the potential for producing an allergic reaction, side effects or anomalous results. Other approaches have been taken, for example, U.S. Pat. No. 6,669,260, describes an invasive procedure in which the occlusion is surgically aspirated from the vessel. Surgical procedures are characteristically more costly, require greater expertise and may have to be repeated periodically. The methods of treatment described in the patents are therefore not entirely satisfactory. Consequently, the need still exists for a more effective system for treating intimal hyperplasia.
In view of these and other shortcomings of the prior art, it is one objective of the present invention to provide a new method and apparatus for preventing dialysis graft intimal hyperplasia which is well tolerated by the patient and which does not cause discernable damage to surrounding body tissue.
Another object of the invention is to provide a new method and apparatus of the type described which can be readily produced at a reasonable cost and is suited for wide scale use and distribution.
Another objective of the invention is to provide a new method and apparatus of the type described which can be carried out effectively while a surgical procedure is being performed, typically, in about 1-2 hours.
Yet another objective of the invention is to provide a new method and apparatus of the type described which can be provided in a compact package that is small enough to be attached to or carried by the patient without undue discomfort or inconvenience.
These and other more detailed and specific objects of the present invention will be better understood by reference to the following figures and detailed description which illustrate by way of example but a few of the various forms of the invention within the scope of the appended claims.